Operating System Internals and Administration Questions

Fundamental and advanced operating system concepts that underlie system administration across platforms. Topics include process and thread management, scheduling and concurrency, memory management and swapping, virtual memory and page replacement, input output and disk performance, file system architecture and semantics, system call interfaces, kernel parameters and tuning, authentication and permission models, boot and initialization sequences, monitoring and system performance analysis, and general techniques for debugging and diagnosing systemic operating system issues. Candidates should be able to explain not only how to perform administrative tasks but why the underlying mechanisms behave as they do and how design choices affect performance and reliability.

MediumTechnical

114 practiced

A database workload under heavy writes shows high write latency. From the OS and filesystem perspective, what tuning options and changes would you consider: I/O scheduler (noop/mq-deadline), elevator settings, readahead, mount options (noatime, data=writeback/data=journal), filesystem choice and block-size, RAID stripe alignment, and SSD TRIM? Outline experiments to measure the impact of each change safely.

MediumTechnical

56 practiced

Provide an /etc/sudoers snippet (formatted for visudo) that allows a specific user 'deploy' to run only the following commands as root without a password: /usr/bin/systemctl restart myapp.service and /usr/bin/journalctl -u myapp.service. Explain security considerations and how you would test this setup safely.

EasyTechnical

78 practiced

Write a Bash one-liner or short script to find the top 10 largest regular files under /var and print file size (human readable), full path, and inode. The script must avoid descending into other mounted filesystems and handle spaces and special characters in filenames. Specify the commands you would use and any options required.

MediumTechnical

61 practiced

Explain the major process scheduling strategies used by operating systems (round-robin, priority-based, multilevel-feedback queue) and describe how Linux's Completely Fair Scheduler (CFS) approximates fairness. Explain what 'nice' values change and list kernel tunables that influence scheduling latency and granularity.

EasyTechnical

64 practiced

Explain swap space (Linux) and pagefile (Windows): what they are, when the OS moves pages to swap, the performance implications of swapping, and practical steps to configure, inspect, or safely disable swap/pagefile. Provide commands you would use to view swap usage and activity.

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